1. Introduction
The present invention is generally related to a novel apparatus for mounting printed circuit boards in a stacked coaxial relationship to one another as conventionally done for components in electrical equipment, e.g. aircraft instrumentation. More particularly, the present invention provides a novel system for the stacked assembly of printed circuit boards which facilitates the eccentric pivotal movement and isolation of selected boards out of the coaxial relationship so as to facilitate the manufacture, and/or repair thereof.
As used herein, the term "coaxial relationship" refers to the usual stacked alignment and mounting of individual circuit boards one on top of another or one behind the other, etc. Additionally, the term "eccentric pivotal movement" or like terms refers to pivotal movement of each of the circuit boards about a transverse axis passing through other than the geometric center of the board.
In accordance with the present invention selected ones of a plurality of coaxially assembled, or "stacked", printed circuit boards can be eccentrically pivoted about an axis tranverse to the individual planes of such circuit boards so as to selectively move them out of the coaxial assemblage. Moreover, wiring which interconnects the individual circuit boards of the assembly is neatly and conveniently housed in an interconnecting structure which not only defines the axis of pivotal movement for the circuit boards but also facilitates such pivotal movement by establishing a wiring manifold at least partially coincident with the pivotal axis which thus enables eccentric pivotal movement of the individual circuit boards to occur without substantially disturbing the interconnecting wiring system of the assembly.
2. Description of the Prior Art
Those in the art to which the present invention pertains have continually sought improved means for contiguously mounting an assembly of printed circuit boards as evidenced, for example, by reference to U.S. Pat. No. 4,161,017 to Pierce et al; U.S. Pat. No. 3,539,874 to Swanson; and U.S. Pat. No. 2,796,559 to Feucht.
Pierce et al disclose a prior art device which permits pivotal movement of printed circuit boards about axes within or parallel to the planes defined by respective circuit boards. Thus, according to the proposal of Pierce et al, if a circuit board located relatively deep in the stack is to be isolated, all circuit boards prior to the desired board must be successfully pivoted about their different respective axes to permit unobstructed access thereto. This arrangement is particularly disadvantageous if the circuit board assembly is located in an area of severe spatial limitations. Moreover, since the Pierce et al device contemplates pivotal movement about stacked axes, sufficient slack wire must be provided to permit the extent of pivotal movement necessary for each of the circuit boards in the assembly. It is surmised that upon pivotal movement of the circuit boards, portions of such slack wire may become pinched between the hinge mechanisms or otherwise restrict the intended hinge movements or be exposed to potential damage.
Swanson discloses that a cradle structure having a plurality of spaced slots can be utilized to hold a stacked arrangement of printed circuit boards. However, as depicted in FIGS. 2 and 3 of the Swanson patent, when predetermined ones of the circuit boards are desired to be removed, they are simply lifted out of the engaging relationship with their associated slot. This form of an arrangement, therefore, utilizes only the interconnecting wiring per se as a means of maintaining the integrity of the assembly when one or more boards are removed from the cradle which could place unnecessary and potentially damaging stresses upon the points of wiring contact with the circuit boards.
Feucht discloses that a rigid spacer member can be utilized in combination with a plurality of circuit boards so as to maintain the separation distance therebetween. However, Feucht does not contemplate pivotal movement of any of the circuit boards comprising his assembly as his main concern is with providing an apparatus for an assembly of circuit boards which operates as a heat sink so as to dissipate sink generated by the individual electrical components comprising his assembly.
3. Summary of the Present Invention
As the reader will undoubtedly appreciate, the above prior art proposals have disadvantages with respect to ease of access to an individual printed circuit board, and with respect to the placement of undue stresses upon the interconnecting wiring.
Briefly stated, the present invention is particularly adapted to an improved assembly of stacked printed circuit boards so as to facilitate manufacturing and/or repair. According to the present invention an elongated wiring manifold is provided which transversely connects the circuit boards and also establishes a transverse axis of rotation about which the individual boards comprising the assembly can be eccentrically rotated or pivoted. Furthermore, the wiring manifold serves as a receptacle or housing for the interconnecting wiring thereby ensuring that such wiring is substantially undisturbed during pivotal movement of the circuit boards. The manifold is provided with circuit board engageable portions spaced along its axial dimension at predetermined intervals so as to establish the desired separation distance between adjacent circuit boards. To ensure that circuit boards pivoted out of alignment with the others are freely accessible, it is desirable to establish the pivotal point of connection with the manifold at a point near the circumferential edge of each board (e.g. at a point far removed from the board center point).
To establish a rigid union between the individual circuit boards in their normal coaxial position yet to permit predetermined eccentric pivotal movement thereof about the transverse axis defined by the wiring manifold, I prefer to provide a mounting spacer leg or equivalent structures which can be moved into and out of an engageable relationship with the circuit boards in the assembly. Preferably, the mounting spacer leg is disposed opposite and parallel to the wiring manifold and defines a plurality of seats or notches spaced along its axial length corresponding to the desired separation distances of the circuit boards in the assembly. A roll pin can be provided on one end of the mounting spacer leg which cooperates with aperture-defining lobes formed on a suitable backing plate so as to establish a hinged connection therewith.
Thus, when structural rigidity is required (e.g. when the circuit boards are in their normal coaxial relationship), the mounting spacer leg need only be pivoted into an engaged relationship with the individual circuit boards so as to permit the seats defined by the mounting spacer leg to register with a corresponding edge portion of each of the circuit boards. Of course, when required, the mounting spacer leg can be disengaged from the circuit boards by virtue of its hinged movement and selected ones of the circuit boards can thereafter be eccentrically pivoted out of their normal coaxial relationship about the wiring manifold as has been briefly described above.
Further advantages and objects of the present invention will become more clear to the reader after careful consideration is given to the following detailed description of the presently preferred exemplary embodiment: